Patent GB-825937-A (GB)
Title: Improvements in or relating to electric incandescent filament lamps
Inventor: DESHAW ZOLTAN
IPC: H01K3/00
Filed: 1956-02-13
Abstract: 825,937. Making electric incandescent lamps. ISMAY LAMPS Ltd. Feb. 13, 1956, No. 4472/56. Class 39(2) The filament supporting wires 9, Fig. 1, which radiate from a glass stud 3 at the end of the central glass rod or arbor 2 of a lamp mount are medially bent to shorten the distance between their point of emergence from the stud and their filament-engaging end, by giving alternate wires an upward or downward bend at or near their middle points, from an initial horizontal plane at right angles to the lamp axis, and then giving the downwardly bent wires an upward bend at their point of emergence from the stud, and the upwardly bent wires a downward bend at their point of emergence from the stud, with the result that the filament extends around the mount in a zig-zag path. The inner and outer sections into which each radial filament-supporting wire is formed by its intermediate bend may include between them an angle of 55 degrees to 125 degrees, an angle of 90 degrees or approximately 90 degrees being preferable. During the first stage the intermediate bending of the filament supporting wires 9 is accompanied by bending of the leading-in wires or electrodes 6 which are swung inwardly towards the axis of the mount about their points of emergence from the pinch, and at the second stage a medial bend is imparted to these wires, bringing their filament contacting extremities still further inwards to avoid stretching of the filament as a result of the bending of the supporting wires 9. The operations are effected by apparatus at sequential work stations to which the mount is indexed while mounted in one of the heads of a lamp-making machine. Fig. 3 shows the apparatus at the first bending station comprising a stationary lower former 11 and a co-operating upper former 12 that is secured on a spindle 13 carried by a rocking lever 14 and vertically displaceable therein. Lever 14 is pivoted on a pin 15 supported by a pillar 16. A rod 17 displaceable vertically within the pillar 16 by a cam (not shown) carries an abutment cam 18 and an adjustable abutment screw 19 which co-operate with a lever 20 secured to the spindle 13 and carrying a roller 20a, whereby vertical reciprocation of rod 17 causes the upper former 12 to swing laterally towards and away from the full line position shown in the Figure. In operation the lamp mount, which is held by the jaws of its carrier head gripping the glass rod 2 as shown in Fig. 4, is halted just over the lower former 11 and then lowered under cam action so that the supporting wires 9 make contact with the former 11 and are swung upwardly through a small angle about their points of emergence from the stud 3, the upper former 12 being meanwhile to the left of its operative position. The upper former is then swung inwardly during initial downward movement of the rod 17 and is lowered by further downward movement of the latter, the spindle 13 being moved downwardly against the pressure of a spring 22, so that the upper former 12 is brought down on to the lower former 11, as shown in Fig. 4a, and a 90 degree bend is formed centrally in each supporting wire 9, the oppositely disposed wires being bent in opposite directions by the parts 23 and 24 on the lower die engaging the corresponding parts 25 and 26 of the upper die. In the example the mount has seven filament-supporting wires 9, of which three are engaged by the projections 23 of the lower die and four are engaged by projections 26 depending from the former 12. Peripheral grooves 11a in the former 11 accommodate the pigtails whichengage the filament at the ends of the wires 9. Pre-positioning of the leading-in wires 6 is effected by a rear centralizer plate 36 carried by an arm 37, and two lateral centralizing plates 38 carried by a pair of side arms 39, one in front of, and the other behind, the arm 37. The side arms 39 are movable in unison towards and away from one another in a plane at right angles to the plane of the Figure.